Eamus, many thanks for pulling it together. Excellent stuff.

One question and one comment:

The continents are counted even if you only change planes there (eg. stopping in Asia on a flight from Europe to Australia), and the continent count includes the continent of origin.

and

You can backtrack within countries and continents, but you cannot re-enter a continent after leaving it, except: (a) a transit without stopover in Asia on a flight between Europe and SWP or vice versa,

Is the order relevant? Could you do a one-segment Europe to Australia flight and then re-enter Asia to travel around? The way I parse this means that the non-stopover transit continent re-entry has to come after you've done your traveling in the continent which you're re-entering. I.e. you can't do LHR-SIN-SYD-MEL-BNE-SYD-SIN-BKK-HGK-... route.

The flights across the Atlantic and Pacific Oceans do not count against any continent allowance, although obviously they do count against your 20 segment total allowance. There are, in addition, other restrictions you need to be aware of.

None of the intercontinental flights count towards the 20 segment limit, not just the transoceanic ones. If you fly LHR-CPT, it's an intercontinental flight, and does not count towards either the Europe or Africa stops.